/*
 * multilink.c - support routines for multilink.
 *
 * Copyright (c) 2000-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && defined(HAVE_MULTILINK) /* don't build if not configured    \
                                              for use in lwipopts.h */

/* Multilink support
 *
 * Multilink uses Samba TDB (Trivial Database Library), which
 * we cannot port, because it needs a filesystem.
 *
 * We have to choose between doing a memory-shared TDB-clone,
 * or dropping multilink support at all.
 */

#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"
#include "netif/ppp/lcp.h"
#include "netif/ppp/tdb.h"

bool endpoint_specified; /* user gave explicit endpoint discriminator */
char *bundle_id;         /* identifier for our bundle */
char *blinks_id;         /* key for the list of links */
bool doing_multilink;    /* multilink was enabled and agreed to */
bool multilink_master;   /* we own the multilink bundle */

extern TDB_CONTEXT *pppdb;
extern char db_key[];

static void make_bundle_links(int append);
static void remove_bundle_link(void);
static void iterate_bundle_links(void (*func)(char *));

static int get_default_epdisc(struct epdisc *);
static int parse_num(char *str, const char *key, int *valp);
static int owns_unit(TDB_DATA pid, int unit);

#define set_ip_epdisc(ep, addr)                                                \
  do {                                                                         \
    ep->length = 4;                                                            \
    ep->value[0] = addr >> 24;                                                 \
    ep->value[1] = addr >> 16;                                                 \
    ep->value[2] = addr >> 8;                                                  \
    ep->value[3] = addr;                                                       \
  } while (0)

#define LOCAL_IP_ADDR(addr)                                                    \
  (((addr)&0xff000000) == 0x0a000000     /* 10.x.x.x */                        \
   || ((addr)&0xfff00000) == 0xac100000  /* 172.16.x.x */                      \
   || ((addr)&0xffff0000) == 0xc0a80000) /* 192.168.x.x */

#define process_exists(n) (kill((n), 0) == 0 || errno != ESRCH)

void mp_check_options() {
  lcp_options *wo = &lcp_wantoptions[0];
  lcp_options *ao = &lcp_allowoptions[0];

  doing_multilink = 0;
  if (!multilink)
    return;
  /* if we're doing multilink, we have to negotiate MRRU */
  if (!wo->neg_mrru) {
    /* mrru not specified, default to mru */
    wo->mrru = wo->mru;
    wo->neg_mrru = 1;
  }
  ao->mrru = ao->mru;
  ao->neg_mrru = 1;

  if (!wo->neg_endpoint && !noendpoint) {
    /* get a default endpoint value */
    wo->neg_endpoint = get_default_epdisc(&wo->endpoint);
  }
}

/*
 * Make a new bundle or join us to an existing bundle
 * if we are doing multilink.
 */
int mp_join_bundle() {
  lcp_options *go = &lcp_gotoptions[0];
  lcp_options *ho = &lcp_hisoptions[0];
  lcp_options *ao = &lcp_allowoptions[0];
  int unit, pppd_pid;
  int l, mtu;
  char *p;
  TDB_DATA key, pid, rec;

  if (doing_multilink) {
    /* have previously joined a bundle */
    if (!go->neg_mrru || !ho->neg_mrru) {
      notice("oops, didn't get multilink on renegotiation");
      lcp_close(pcb, "multilink required");
      return 0;
    }
    /* XXX should check the peer_authname and ho->endpoint
       are the same as previously */
    return 0;
  }

  if (!go->neg_mrru || !ho->neg_mrru) {
    /* not doing multilink */
    if (go->neg_mrru)
      notice("oops, multilink negotiated only for receive");
    mtu = ho->neg_mru ? ho->mru : PPP_DEFMRU;
    if (mtu > ao->mru)
      mtu = ao->mru;
    if (demand) {
      /* already have a bundle */
      cfg_bundle(0, 0, 0, 0);
      ppp_netif_set_mtu(pcb, mtu);
      return 0;
    }
    make_new_bundle(0, 0, 0, 0);
    set_ifunit(1);
    ppp_netif_set_mtu(pcb, mtu);
    return 0;
  }

  doing_multilink = 1;

  /*
   * Find the appropriate bundle or join a new one.
   * First we make up a name for the bundle.
   * The length estimate is worst-case assuming every
   * character has to be quoted.
   */
  l = 4 * strlen(peer_authname) + 10;
  if (ho->neg_endpoint)
    l += 3 * ho->endpoint.length + 8;
  if (bundle_name)
    l += 3 * strlen(bundle_name) + 2;
  bundle_id = malloc(l);
  if (bundle_id == 0)
    novm("bundle identifier");

  p = bundle_id;
  p += slprintf(p, l - 1, "BUNDLE=\"%q\"", peer_authname);
  if (ho->neg_endpoint || bundle_name)
    *p++ = '/';
  if (ho->neg_endpoint)
    p += slprintf(p, bundle_id + l - p, "%s", epdisc_to_str(&ho->endpoint));
  if (bundle_name)
    p += slprintf(p, bundle_id + l - p, "/%v", bundle_name);

  /* Make the key for the list of links belonging to the bundle */
  l = p - bundle_id;
  blinks_id = malloc(l + 7);
  if (blinks_id == NULL)
    novm("bundle links key");
  slprintf(blinks_id, l + 7, "BUNDLE_LINKS=%s", bundle_id + 7);

  /*
   * For demand mode, we only need to configure the bundle
   * and attach the link.
   */
  mtu = LWIP_MIN(ho->mrru, ao->mru);
  if (demand) {
    cfg_bundle(go->mrru, ho->mrru, go->neg_ssnhf, ho->neg_ssnhf);
    ppp_netif_set_mtu(pcb, mtu);
    script_setenv("BUNDLE", bundle_id + 7, 1);
    return 0;
  }

  /*
   * Check if the bundle ID is already in the database.
   */
  unit = -1;
  lock_db();
  key.dptr = bundle_id;
  key.dsize = p - bundle_id;
  pid = tdb_fetch(pppdb, key);
  if (pid.dptr != NULL) {
    /* bundle ID exists, see if the pppd record exists */
    rec = tdb_fetch(pppdb, pid);
    if (rec.dptr != NULL && rec.dsize > 0) {
      /* make sure the string is null-terminated */
      rec.dptr[rec.dsize - 1] = 0;
      /* parse the interface number */
      parse_num(rec.dptr, "IFNAME=ppp", &unit);
      /* check the pid value */
      if (!parse_num(rec.dptr, "PPPD_PID=", &pppd_pid) ||
          !process_exists(pppd_pid) || !owns_unit(pid, unit))
        unit = -1;
      free(rec.dptr);
    }
    free(pid.dptr);
  }

  if (unit >= 0) {
    /* attach to existing unit */
    if (bundle_attach(unit)) {
      set_ifunit(0);
      script_setenv("BUNDLE", bundle_id + 7, 0);
      make_bundle_links(1);
      unlock_db();
      info("Link attached to %s", ifname);
      return 1;
    }
    /* attach failed because bundle doesn't exist */
  }

  /* we have to make a new bundle */
  make_new_bundle(go->mrru, ho->mrru, go->neg_ssnhf, ho->neg_ssnhf);
  set_ifunit(1);
  ppp_netif_set_mtu(pcb, mtu);
  script_setenv("BUNDLE", bundle_id + 7, 1);
  make_bundle_links(pcb);
  unlock_db();
  info("New bundle %s created", ifname);
  multilink_master = 1;
  return 0;
}

void mp_exit_bundle() {
  lock_db();
  remove_bundle_link();
  unlock_db();
}

static void sendhup(char *str) {
  int pid;

  if (parse_num(str, "PPPD_PID=", &pid) && pid != getpid()) {
    if (debug)
      dbglog("sending SIGHUP to process %d", pid);
    kill(pid, SIGHUP);
  }
}

void mp_bundle_terminated() {
  TDB_DATA key;

  bundle_terminating = 1;
  upper_layers_down(pcb);
  notice("Connection terminated.");
#if PPP_STATS_SUPPORT
  print_link_stats();
#endif /* PPP_STATS_SUPPORT */
  if (!demand) {
    remove_pidfiles();
    script_unsetenv("IFNAME");
  }

  lock_db();
  destroy_bundle();
  iterate_bundle_links(sendhup);
  key.dptr = blinks_id;
  key.dsize = strlen(blinks_id);
  tdb_delete(pppdb, key);
  unlock_db();

  new_phase(PPP_PHASE_DEAD);

  doing_multilink = 0;
  multilink_master = 0;
}

static void make_bundle_links(int append) {
  TDB_DATA key, rec;
  char *p;
  char entry[32];
  int l;

  key.dptr = blinks_id;
  key.dsize = strlen(blinks_id);
  slprintf(entry, sizeof(entry), "%s;", db_key);
  p = entry;
  if (append) {
    rec = tdb_fetch(pppdb, key);
    if (rec.dptr != NULL && rec.dsize > 0) {
      rec.dptr[rec.dsize - 1] = 0;
      if (strstr(rec.dptr, db_key) != NULL) {
        /* already in there? strange */
        warn("link entry already exists in tdb");
        return;
      }
      l = rec.dsize + strlen(entry);
      p = malloc(l);
      if (p == NULL)
        novm("bundle link list");
      slprintf(p, l, "%s%s", rec.dptr, entry);
    } else {
      warn("bundle link list not found");
    }
    if (rec.dptr != NULL)
      free(rec.dptr);
  }
  rec.dptr = p;
  rec.dsize = strlen(p) + 1;
  if (tdb_store(pppdb, key, rec, TDB_REPLACE))
    error("couldn't %s bundle link list", append ? "update" : "create");
  if (p != entry)
    free(p);
}

static void remove_bundle_link() {
  TDB_DATA key, rec;
  char entry[32];
  char *p, *q;
  int l;

  key.dptr = blinks_id;
  key.dsize = strlen(blinks_id);
  slprintf(entry, sizeof(entry), "%s;", db_key);

  rec = tdb_fetch(pppdb, key);
  if (rec.dptr == NULL || rec.dsize <= 0) {
    if (rec.dptr != NULL)
      free(rec.dptr);
    return;
  }
  rec.dptr[rec.dsize - 1] = 0;
  p = strstr(rec.dptr, entry);
  if (p != NULL) {
    q = p + strlen(entry);
    l = strlen(q) + 1;
    memmove(p, q, l);
    rec.dsize = p - rec.dptr + l;
    if (tdb_store(pppdb, key, rec, TDB_REPLACE))
      error("couldn't update bundle link list (removal)");
  }
  free(rec.dptr);
}

static void iterate_bundle_links(void (*func)(char *)) {
  TDB_DATA key, rec, pp;
  char *p, *q;

  key.dptr = blinks_id;
  key.dsize = strlen(blinks_id);
  rec = tdb_fetch(pppdb, key);
  if (rec.dptr == NULL || rec.dsize <= 0) {
    error("bundle link list not found (iterating list)");
    if (rec.dptr != NULL)
      free(rec.dptr);
    return;
  }
  p = rec.dptr;
  p[rec.dsize - 1] = 0;
  while ((q = strchr(p, ';')) != NULL) {
    *q = 0;
    key.dptr = p;
    key.dsize = q - p;
    pp = tdb_fetch(pppdb, key);
    if (pp.dptr != NULL && pp.dsize > 0) {
      pp.dptr[pp.dsize - 1] = 0;
      func(pp.dptr);
    }
    if (pp.dptr != NULL)
      free(pp.dptr);
    p = q + 1;
  }
  free(rec.dptr);
}

static int parse_num(str, key, valp)
char *str;
const char *key;
int *valp;
{
  char *p, *endp;
  int i;

  p = strstr(str, key);
  if (p != 0) {
    p += strlen(key);
    i = strtol(p, &endp, 10);
    if (endp != p && (*endp == 0 || *endp == ';')) {
      *valp = i;
      return 1;
    }
  }
  return 0;
}

/*
 * Check whether the pppd identified by `key' still owns ppp unit `unit'.
 */
static int owns_unit(key, unit)
TDB_DATA key;
int unit;
{
  char ifkey[32];
  TDB_DATA kd, vd;
  int ret = 0;

  slprintf(ifkey, sizeof(ifkey), "IFNAME=ppp%d", unit);
  kd.dptr = ifkey;
  kd.dsize = strlen(ifkey);
  vd = tdb_fetch(pppdb, kd);
  if (vd.dptr != NULL) {
    ret = vd.dsize == key.dsize && memcmp(vd.dptr, key.dptr, vd.dsize) == 0;
    free(vd.dptr);
  }
  return ret;
}

static int get_default_epdisc(ep)
struct epdisc *ep;
{
  char *p;
  struct hostent *hp;
  u32_t addr;

  /* First try for an ethernet MAC address */
  p = get_first_ethernet();
  if (p != 0 && get_if_hwaddr(ep->value, p) >= 0) {
    ep->class = EPD_MAC;
    ep->length = 6;
    return 1;
  }

  /* see if our hostname corresponds to a reasonable IP address */
  hp = gethostbyname(hostname);
  if (hp != NULL) {
    addr = *(u32_t *)hp->h_addr;
    if (!bad_ip_adrs(addr)) {
      addr = lwip_ntohl(addr);
      if (!LOCAL_IP_ADDR(addr)) {
        ep->class = EPD_IP;
        set_ip_epdisc(ep, addr);
        return 1;
      }
    }
  }

  return 0;
}

/*
 * epdisc_to_str - make a printable string from an endpoint discriminator.
 */

static char *endp_class_names[] = {"null", "local", "IP",
                                   "MAC",  "magic", "phone"};

char *epdisc_to_str(ep)
struct epdisc *ep;
{
  static char str[MAX_ENDP_LEN * 3 + 8];
  u_char *p = ep->value;
  int i, mask = 0;
  char *q, c, c2;

  if (ep->class == EPD_NULL && ep->length == 0)
    return "null";
  if (ep->class == EPD_IP && ep->length == 4) {
    u32_t addr;

    GETLONG(addr, p);
    slprintf(str, sizeof(str), "IP:%I", lwip_htonl(addr));
    return str;
  }

  c = ':';
  c2 = '.';
  if (ep->class == EPD_MAC && ep->length == 6)
    c2 = ':';
  else if (ep->class == EPD_MAGIC && (ep->length % 4) == 0)
    mask = 3;
  q = str;
  if (ep->class <= EPD_PHONENUM)
    q += slprintf(q, sizeof(str) - 1, "%s", endp_class_names[ep->class]);
  else
    q += slprintf(q, sizeof(str) - 1, "%d", ep->class);
  c = ':';
  for (i = 0; i < ep->length && i < MAX_ENDP_LEN; ++i) {
    if ((i & mask) == 0) {
      *q++ = c;
      c = c2;
    }
    q += slprintf(q, str + sizeof(str) - q, "%.2x", ep->value[i]);
  }
  return str;
}

static int hexc_val(int c) {
  if (c >= 'a')
    return c - 'a' + 10;
  if (c >= 'A')
    return c - 'A' + 10;
  return c - '0';
}

int str_to_epdisc(ep, str)
struct epdisc *ep;
char *str;
{
  int i, l;
  char *p, *endp;

  for (i = EPD_NULL; i <= EPD_PHONENUM; ++i) {
    int sl = strlen(endp_class_names[i]);
    if (strncasecmp(str, endp_class_names[i], sl) == 0) {
      str += sl;
      break;
    }
  }
  if (i > EPD_PHONENUM) {
    /* not a class name, try a decimal class number */
    i = strtol(str, &endp, 10);
    if (endp == str)
      return 0; /* can't parse class number */
    str = endp;
  }
  ep->class = i;
  if (*str == 0) {
    ep->length = 0;
    return 1;
  }
  if (*str != ':' && *str != '.')
    return 0;
  ++str;

  if (i == EPD_IP) {
    u32_t addr;
    i = parse_dotted_ip(str, &addr);
    if (i == 0 || str[i] != 0)
      return 0;
    set_ip_epdisc(ep, addr);
    return 1;
  }
  if (i == EPD_MAC && get_if_hwaddr(ep->value, str) >= 0) {
    ep->length = 6;
    return 1;
  }

  p = str;
  for (l = 0; l < MAX_ENDP_LEN; ++l) {
    if (*str == 0)
      break;
    if (p <= str)
      for (p = str; isxdigit(*p); ++p)
        ;
    i = p - str;
    if (i == 0)
      return 0;
    ep->value[l] = hexc_val(*str++);
    if ((i & 1) == 0)
      ep->value[l] = (ep->value[l] << 4) + hexc_val(*str++);
    if (*str == ':' || *str == '.')
      ++str;
  }
  if (*str != 0 || (ep->class == EPD_MAC && l != 6))
    return 0;
  ep->length = l;
  return 1;
}

#endif /* PPP_SUPPORT && HAVE_MULTILINK */
